How many days do puppies need to be vaccinated?

Puppies receive the first vaccine injection 45 days after birth. If vaccinated too early, maternal antibodies will neutralize the vaccine, affect the immune effect and consume the antibodies, which will have the opposite effect. It will not work if it is too late and it cannot guarantee health. Therefore 45 days is optimal.
The first vaccination for dogs generally requires 3 shots, with an interval of about 20 days. After the second year, you can get just one shot. Generally, after vaccination, you will be given a red vaccination booklet with the vaccination time on it. In the second year, I went for the injection about a month in advance. Finally, inject regularly according to the time strictly.